Electric signal lamp



C. ADLER, JR

Nov. 29, 1 932.

ELECTRIC S IGNAL LAMP Filed April 6, 1932 3 Sheets-Sheet Nov. 29, 1932. c. ADLER, JR

ELECTRIC SIGNAL LAMP Filed April 6, 1952 3 Sheets-Sheet 2 a 8 w w J CizarZes fldlerx Cv ADLER JR Nov. 29, 193?.

ELECTRIC SIGNAL LAMP 3 Sheets-Sheet 3 Filed April 6, 1932 Cfiarles Adler; J7,

Patented Nov, 29, 1932 CHARLES ADLER, .13., OF

BALTIMORE, MARYLAND ntnc'rnro. srsnnn LAMP Application filed April 6,

This invention relates generally to electric signal lamps and more particularly to such lamps designed for traiiic and railroad signal purposes.

The primary ob cct of the invent on is to provide an electric signal lamp having a plurality of filaments of substantially equal capacity and electrically 1n parallel and sand lamp also having a normally inactive means, i. e., a screen, interposed between sa1d filaments whereby when installed in a signal system, should burning outof one of said filaments occur, the screen will act to produce with the other energized filament, an indica- 5 tion of the failure of one filament by producing definite c ntrasting bright and dark areas within the lamps. In this manner the lamp remains operative for signal purposes.

It is, therefore, the primary object of the invention to produce an indicator lamp char acterized by the use of an indicator screen interposed between the filaments of the lamp which are permanently and completely electrically connected in parallel, that is, adapted to be simultaneously and continuously energized and not capable of being independently energized by a switch or other equivalent electrical device; and so that when one filament burns out, the screen is operable with the remaining incandescent filament to produce (l) .the desired and definite indication of the filler, and (2) immediately and simultaneously with such indication a definite signal indication, when the operability of the signal system is not impaired. In this concept and the construction whereby it is carried out, the invention distinguishes from conventional expedients.

Two filament lamps have been used for railroad signal purposes, but have been found inadequate, because with both filaments disposed substantially at the focal point of the optical system, the reduction of intensity is not noticeable when one filament burns out,

particularly when viewed through a lens ofeolored glass.

While my lamp may be utilized for many different purposes, it is particular ly adapted for use in connection with street trafiic or 1932. Serial No. 603,627.

railroad signal systems where it is imperative that the signal area be illuminated, and where failure of such area to be illum nated may cause serious accidents. Many accidents r have been caused by the burning out of lamps behind the red lenses of traliic signals. When a failure of this sort occurs, an extremely hazardous condition is established, especially when the green signals facing the intersecting highway are displayed. The motorist who C3 should be receiving an indication to stop, is given no indication at all while motorists on the intersecting highway are at the same time being informed that the way is clear. At night, this condition is especially dangerous. With my improved lamp construction, this dangerous condition is entirely eliminated. Upon failure of one filament, the remaining filament in the lamp will continue to function but because of the interposition of the screen between the filaments the signal indication given will produce contrasting light areas, and thus give warning that the lamp should be replaced.

Usually, such traflic signals, or so called 0 traffic lights, comprise a housing with which is associated a'reflector' and a cover glassor lenses together with a conventional incandescent lamp, whereby parallel horizontal beams of light are produced. With my invention, this important result is achieved without interfering with the safety factor described or modifying the structure of the housing and associated parts. a I

My lamp is also of specific importance and advantage in railway signaling. Here a reflector is sometimes omitted and the optical system, i. e., the lamp and lenses, adjusted so that the lamp will give parallel horizontal beams. Thescrailway signals employ housings, and while heretofore some multiple fi1a-' ment lampshave been utilized, they are not satisfactory because the reduction in intensity caused by failure of a filament is not readily observable. This is due to the location of the filaments with respect to the focal point of the lenses. In this very vital field of signal ing, my improved lamp with its screen meets the problem and should a failure of onefilament occur, therewvill, simultaneouslywith about the non-glare or such failure, be observable to the unpractised ferent fuhction and structure bein deslgned to control and restrain projection light on a 1 roadwa and cannot be satisfactorily employed mtraflic or railway signals.

Referring now to the drawm Figure 1 is a side elevation 0 one form of my signal lamp, with a portion of the bulb broken away. u

Figure 2-is a section through line 2-2 of Fi e-1.

igure 3 is a modified form-of my signal lamp with a portion of the bulb broken away.

' Figure 4 is a section on'the line 4'4 of Figq in Figure 7.

ure 3.

Figure 5 is a horizontal sectional view of a casing with m signal lamp applied thereto,

viewed from t e-top. Figure 6 is a detailof the screen shown in Fi 1 and 2.

igure 7 is a front elevation of another modification of my lamp.

Figure 8 is a top view ammatic view of the ciraments of the lamp of Figure9is adi cuit throu h the Fi 7 an '8.

igure 10 is a view showing the signal lamp of Pi res 7 and 8 ositioned in a caslampin andwit respecttoa ens.

igure 11 is a detail of the screen shown in F1gures7 and '8. a

Figure 12 is a face view showing my signal itioned in a signal casing having a colore covered glass andin which a parabolic reflector is used, this'view also showing the lighting efi'ect when one filament is burn out; and

p Figure 13 is a top view ofthe lamp used in an optical system wherein the reflector is omitted and an opticallens is emplo ed, this view also showin the lighting e ect when one filament of this lamp is burned out.

Referring now to the drawings, and particularly to Figures 1 and 2, the numeral 10 indicates one orm of my improved signal, i. e. indicator lamp, comprising the usual threaded base rtion or shell 11, and socket contact 11' an 'a conventional evacuated or gas-filled glass bulb 12 secured thereto in the usual manner. The lam has a single leadin, and a single lead-out for contact with the screen, 16, also pre of the lamp shown accommodate a thin polished interposed screen, and in the case of a metal screen, a distance such that there will be no danger of shortcircuiting.

Interposed between the slightly spaced filaments and coincident the longitudiis a dIViSiOll plate, or.

nal axis of the lam f rably supported by the pillar 13, by, means of a suitable wire or wires 17. In the form of my invention, shown in Figs. 1 and 2, this screen is opaque, and comprises a highly polished and thin metallic plate of heat resistant metal. The invention, however, is not limited to this type of screen, as the same may be constructe of transparent or translucent material, or of mica.v

y The filaments extend transversely to the" longitudinal axis of the lamp, as shown in Figure 2, and are in substantially the same transverse plane, being symmetrically positioned with respect to the screen. They are electrically in parallelwhereby both filaments are continuously energized and, so that if one filament burns out, the other will still function properly. I

When a lamp such as describedabove is placed in use, both filaments will be made incandescent, and will. give a uniform lighting effect, sincr the screen is, under normal circumstances, inactive. If, however, either filament-burns out, the other one will, because of its electrical connection, remain incandescent and will adequately light that side of the lamp upon'which it is positioned with respect to the screen." In other words, the filaments are permanently and completely electrically connected in parallel. I Because of the fact that the screen 16 is formed of opaquematerial, no light will pass through the screen to that side of the lamp upon which ion the burned out filamentis located, and there u will thus be created a dark area at one side of the screen contrasting with the bright area on the opposite side of the screen. These two contrasting areas may or may not be equal in size as viewed from the end of the lamp. The size of the screen will, of course, affect the relative sizes of the two light areas. As shown in the drawings, the screen is of a size to shield the light of one filament from the other. Such an arrangement will, when one filamefit burns out, produce separate contrasting light areas which will clearly be area, there will be an unmistakable notifica-= tion that the lamp should be renewed.

Due to the fact that the two filaments are substantially identical in size and capacity, and also because of the positioning of said filaments and screen with respect to each other as described above, the size or shape of the bright area will always remain uniform regardless of which filament burns out. This is also true of the dark area.

It should be stated that the glass of my lamp may be clear or frosted either internally or externally, as desired. Furthermore, the lamp may be of any other desired configuration. I

Referring now to Figures 3 and 4, there is illustrated a lamp having substantially the same characteristics as the lamp of Figures 1 and 2, with the exception that the screen is to be formed of colored glass instead of being opaque. The lamp is provided with a supporting pillar 18 to which the filaments 19 are secured by supporting wires 20 and 20, the latter constituting part of the electrical circuit of the lamp. A screen 21 s interposed between the filaments and in lJlllS instance comprises a purple or dark blue glass, which is secured to the pillar 18 by means of an elongated extension 22. In use, the effect is different from that obtained with the opaque screen, in that light will pass through the colored screen when one filament is burned out. The arrangement will be such that two light areas will be created, one the usual brilliant area and the other a light area contrasting in intensity and color with the first mentioned area and comprising a darkened area of purple or dark blue hue. In this arrangement, as in the case of the opaque screen, the lamp will be adequately lighted to function, when one filament burns out, but because of the darkened area, there will be an unmistakable notification that the lamp should be renewed.

In Figure 5, I have diagrammatically illustrated my lamp as being applied to a traflic signal casing. The numeral 24 represents the casing having a parabolic reflector 25, and a concave-convex lens 26. As shown, this lens is formed so as to provide a plurality of vertical corrugations 27 on the inner concave side. With this arrangement, parallel beams from the lamp are projected horizontally from the parabolic reflector and amore eflicient distribution of light is effected. The lamp is connected centrally ofthe reflector and the filaments therefore extend vertically and by reason of their spacing with respect to the screen are disposed close to the focal point of the reflector, so that horizontal parallel beams of light are obtained. Of

course, the effective light areas will be substantially enlarged, so that the effect will be that the face of the lens will be divided into bright and dark areas, when one filament burns out. The size and shape of these light areas will be uniform when one filament is out, regardless of which filament fails.

Assuming that the casin 24 is" provided with a red colored lens, an that one of my signal lamps having an opaque screen is installed in the casing, there will be the usual effect when both filaments are incandescent, that is, there will be a single red light area over the entire lens. When, however, either one of the filaments burns out, there will instantly be created two light areas of contrasting intensity such as illustrated in Figure 12. There will be one area of the usual red hue created by the filament which is still incan: descent and positioned on that side ofthe screen. In addition, there will be created a dark area on the side of the opaque screen upon which the burned out filament is located. Thus the signal will be adequately lighted to function, and the presence of the dark area will constitute a notification that the lamp should be renewed.

The form of lamps shown and described in'Figures 1 to 4, while adapted to universal use, are primarily for use in connection with traflic signaling. lamp adapted particularly for railroad signaling, although not limited to this specific use. This modified construction is disclosed in Figures 8 to 11, wherein the lamp 28 is preferably provided with a bayonet base 29. As in the other "lamp structures, I provide a supporting pillar 30, from which are supported spaced V-shaped filaments 31, and interposed between these filaments is an opaque screen 32, also supported from the I have also constructed a pillar 30 and extending coincident with the longitudinal axis of the lamp, this screen preferably comprising a flat circular polished disk of metal. I may, however, employ screens of a contour above shown and described.

As shown in Figure 10, the lamp 28 is preferably disposed vertically when in operative position. In this position the transversely spaced filaments are disposed 'with their apexes pointing toward the top of the lamp, furthermore, while the filaments are in substantially the same transverse plane they do not extend parallel with respect to the screen, but at an angle thereto. Thus the full effect of both legs of each filament is obtained. The rear legs 33 are spaced from the screen while the front legs 34 converge and their free ends contact with, and are electrically connected to the screen, one on each side thereof.

With this arrangement, the screen 32 has the added function of a common ground.

is such that the filaments are in electrical arallel, as in the other forms, so that 1f one filament burns out, the other Wlll function.

As shown in Figure 9, the filaments are permanently and com letely electrically con-.

nected in parallel an there is a single leadin connection and a single lead-out connection in accordance with. this dlagram. Such construction is preferred and is very advantageous and, as stated above, is likewise utilized in the lamps of Fi res 1 to 5, inclusive. The leads terminate pre erably one on the bottom of the base and another at the side thereof for connection with the current supply line being suitably insulated from each other. They may be arranged, however, to terminate at other points if desired. It will be noted, moreover, that with this construction, the parallel connection is sealed within the confines of the lamp. That is, the lamp is a com-- plete unit as shown with the parallel connection in the base of the lamp or in the bulb of Y the lamp. The legs 33 are connected to con-' ductor wires 35, which merge to form the plus terminal 36, while the lower end of the screen is connected to a conductor wire 37 constituting the minus terminal of the circuit.

As stated above, the lamp 28 is partlcularly ada ted for use in railway signaling, and, as s own in Figure 10, is housed within a casin 38 provided with a lens 39. is Is usual in rai way signaling, this houslng 1s not provided with a reflector, as such use liable to produce a phantom when the rays of light from a locomotive headlight come within the 1 placed in use in the casing 38. This will produce a uniform lighting effect, since the screen is, under normal circumstances, inactive. If, however, either filament burns out, the other one will, because of its' electrical connection, remain incandescent, and will adequately light that sideof the lamp upon which it is positioned with respect to the screen 32. As the screen is formed of opaque material, no light will pass through the same to the other side of the lamp upon which the burned'out filament is located, andthus contrastin light and dark areas. will be created. The e ect created when one filament burns out is, clearly illustrated in Figure13.

It is to be observed (1) that the screen is positioned substantially in alignment with the longitudinal axis of the lamp, and (2) that incandescent portions of the filaments .cluded gases given off due to heating of the are only spaced from this screen a sufiicient distance to prevent short circuiting when a metal screen is used i. e., they are as close to the screen as possible and hence are but slightly offset from the longitudinal axis of 7a the lamp. I

- It is to be observed that with any of the several lamps hereindescribed, that the indicator screen is so positioned that whether the lamp occupies a'horizontal or a vertical position, so-long as one edge of the screen aces the objective, it willnot interfere with the projection of li ht forwardly to the objectlve. This is l' ewise true should one filament burn out when, of course, the screen will serve to'prevent hght from passing to the other side of the lamp, as described, but will not interfere with the normal forward projection of light from the remaining incandescent filament to the objective. In this manner the lamp may be positioned in vertical or horizontal positions in accordance with the particular signal optical system. with which it is employed.

This factor is particularly important with the structure shown in Figures 7, 8, 10, 12, employing bent filaments, which present their substantially full incandescent surfaces or filament areas to the objective in any po sition of the lamp and whenan edge of the screen faces the objective.

Furthermore, the screen is of an area to mask, i. e. completely screen the incandescent portions of'the filaments from each otheras shown in the drawings. It will be observed upon reference to the,various lamps that the screen is of relatively small size compared to the bulb and the neck portion thereof. This is important for three reasons, (1 in order to enable the screen to be inserted in the bulb, (2) in order to produce a relatively small cooling area so as not to effect the condition of the interior of the bulb,-and (3) in order to reduce to a minimum the amount of ocscreen. These last twoare of extreme importance, since a largecooling area and a large amount of an ahen gas will pollute the condition prevailing in the interior of the bulb and interfere with the quality of the 1 lamp. 1, therefore, employ ascreen which will be of an area just sufiicient to screen the filaments and produce the desired effect.

By this construction, I am enabled to use the lam (1) in an optical system having a parabolic reflector, or (2) a system wherein the reflector. is omitted and an optical lens employed.

In either case because of the position of the filaments, I am enabled to focus the lamps in accordance with the optical system and from the relationship of one or both filaments to the system, obtain parallel horizontal beams of light. In this manner, a definite signal is presented should one lamp burn out and by was of the position of the filaments with respect to the screen, a clear cut observable area of contrasting darkness is produced, i. e., the notification of the failure is likewise indicated.

As heretofore stated, when both filaments are incandescent, thev screen is inactive i. e., does not substantially affect the luminosity and the lamp may be focused to produce with the optical system employed, parallel beams of light. This condition continues should a filament burn out, and the screen shielding the respective filaments, does not interfere with the proper function of the lamp, but cooperates to produce the contrasting darker area or warning.

It will thus be seen that my improved lamp has combined features which increase the safety factor for signaling purposes.

With regard to the use of two filaments, it s well known that no two lamps or filaments have the same life, and that one will always outlast the other. This is based on experience. The filaments being-connected in parallel, it is safe to assume that, in the event of failure of one filament, a suflicient time will have elapsed to correct the condition before the other filament will burn out, during which period, however, the lamp of the present invention is still operative with the one filament.

In order that there should be no confusion between my novel signal lamp construction and the prior art, it should be stated that I am fully aware that it is old to provide electric illuminating lamps with two filaments having a division plate interposed therebetween. The prior art devices, however, are designed to provide sufficient illumination for highways from vehicle headlights and when it is desired, to extinguish one filament when passing another vehicle, so as to diminish the glare of the headlight on the eyes of the drivers of approaching vehicles and direct it down on the ground. In this prior art, the filaments are either of different size and capacity, or placed at different points with respect to each other and the longitudinal axis of the lamp, or the shield or division plate is so disposed with respect to the fila-- ments, that the beams of light are directed downwardly and to the side when one filament is extinguished, whereas in my invention the filaments are so positioned with respect to the screen and the focal point of the optical system, that the horizontal parallel beams are obtained. Thus in the prior art devices different arrangements of the light and dark areas would be produced when cur;

rent to the different filaments is turned off, and as distinguished from the present invention, there would be no uniformity or fixed bright or dark, area irrespective of which filament was extinguished.

From the foregoing, it will be apparent of the drawings my improved signal lamp associated with a lens I have not herein made any claim to that combination of elements as the same will form the subject matter of a separate application.

In referring to lamps or signal lamps in the specification and claims, I mean lamps of the type adapted to produce an indication as herein set forth. That is to say, an indicator lamp.

The word screen as used in the specification and claims is intended to denote an indicator screen which, when associated with the lamp of the present invention, produces the desired indication when one filament burns out.

The expression permanently and completely electrically connected in parallel is used in the specification and claims to describe my lamp wherein both filaments are adapted one filament burns out, when, because of this permanent and complete parallel connection, and the transverse arrangement of the filaments, the other filament will iluminate a signal area and give a notification of the failure of the burned out filament.

What I claim is: Y

1. An electric indicator lamp comprising a plurality of transversely spaced filaments and an indicator screen tnerebetweenfthe lamp having the filaments permanently and completely electrically connected in parallel and screened from each other by the indicator screen.

2. An electric indicator lamp comprising a plurality of transversely spaced filaments and an indicator screen interposed therebetween, the lamp having the filaments permanently and completely connected in parallel and the parallel connection within the lamp.

3. An electric indicator lamp comprising a plurality of transversely spaced filaments and a substantially opaque indicator screen therebetween, the lamp having the filaments permanently and completely electrically con nected in parallel and screened from each other by the indicator screen.

4. An electric indicator lamp comprising a plurality of transversely spaced filaments and an indicator screen of heat resistant material therebetw'een, the lamp having the filaments permanently and completely electrically connected in parallel and screenedfrom each other by the indicator screen.

5; An electric indicator lamp comprising a plurality of transversely spaced filaments of substantially uniform intensity, and an indicator screen therebetween, said filaments permanently and completely electrically connected in parallel and screened from each other by the indicator screen.

6. An electric indicator lamp comprlsmg a plurality of transversely spaced filaments and an indicator 'scree'n thcrebetween, the lamp havin the filaments permanently and completely e ectricall connected in parallel and so arranged wit respect to the screen as to present substantially their full filament areas in any position of the lamp) and when one edge of the screen faces the o jective.

7. An indicator lamp comprising a plurality of filaments and 'an indicator screen therebetween having substantially plane surfaces, the lamp having the filaments permanently and completely electrically connected in parallel and disposed adjacent the respecof the screen, said tive plane surfaces of the screen.

8. An electric indicator lamp comprising a bulb and a base, a plurality of filaments and an indicator screen therebetween supported by said base, said screen having substantially plane surfaces, the'lamp havin the filaments permanently and complete y electrically connected in parallel and disposed adjacent the respective plane surfaces of the screen.

9. An electric indicator lamp comprising and a translucent indicator screen interposed therebetween, the lamp having the filaments permanentl and comlpletely connected in parallel an the para el connection within the lamp.

'14. An electric indicator lamp comprising a plurality of transversely spaced filaments and an indicator screen interposed therebetween, the lamphaving the filaments permanently and completely connected in parallel, there being a single lead-in contact and a single lead-out contact for establishingconnection of the lamp with the current supply.

' In testimony whereof I aflix m si ature.

CHARLES AD E JR.

a bulb and a base, a plurality of filaments and an indicator screen therebetween su ported by said base, said screen having su electrically connected in parallel and dis posed adjacent the respective plane surfaces parallel connection positioned within the lamp. I

10. An electric indicator lamp comprising a plurality of transversely spaced filaments and an indicator screen of conducting material therebetween, the lamp having the fila- .ments each electrically connected to saidscreen and permanently and com letely electrically connected in parallel, t e-filaments screened from each other by the indicator screen.

11. An electric indicator lam comprising a plurality of bent filaments an an indicator screen therebetween, the lamp having the filaments permanently and completely electrically connected in parallel. and havingone end of each filament supported b said screen, the filaments being 'screene from each other by the indicator screen.

12. An electric indicator lamp comprising a plurality of transversely spaced filaments and a metal indicator screen therebetween,

the lamp having the filaments permanently and completely electrically connected in parallel and screened from each other by the indicator screen.

13. An electric indicator lamp comprising a plurality of transversely spaced filaments 

